FIG. 1 shows a block diagram of a conventional DC/DC (direct-current to direct-current) converter 100. The DC/DC converter 100 includes a full-bridge switching circuit 102, a transformer T1, and a rectifying circuit 106. The full-bridge switching circuit 102 includes switches Q1, Q2, Q3 and Q4, and passes input power, e.g., an input voltage VIN, to the transformer T1 based on controlling of control signals CTR1, CTR2, CTR3 and CTR4 at the switches Q1, Q2, Q3 and Q4. The transformer T1 receives the input power to generate a primary current IPRI flowing through its primary winding. The primary current IPRI induces a corresponding secondary current ISEC flowing through a secondary winding of the transformer T1. The secondary current ISEC further flows through the rectifying circuit 106 to control an output voltage VOUT of the DC/DC converter 100. Thus, by controlling the switches Q1, Q2, Q3 and Q4, the DC/DC converter 100 can convert an input voltage VIN to a desired output voltage VOUT.
As shown in FIG. 1, the control signals CTR1, CTR2, CTR3 and CTR4 can control the switches Q1, Q2, Q3 and Q4 to provide the input power to the transformer T1. The primary current IPRI flows through the transformer T1, and induces magnetic power in the magnetic core of the transformer T1. If the input power is relatively high and causes a relatively large primary current IPRI, the magnetic power stored in the magnetic core of the transformer T1 may produce plenty of heat that cannot be dissipated in a short time. As a result, the transformer T1 may have relatively low power conversion efficiency. The power consumption of the DC/DC converter 100 can be quite high; thus, the performance of power conversion is reduced. A power conversion circuit that addresses this shortcoming would be beneficial.